Transmission and modulation of light beams



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March 28, 1944. s.l F. Afwoon TRANSMISSION AND MODULATION OF LIGHT BEANS Filad lay 22. 1941 March 28, 1944. e, F. A'wOoD TRANSMISSION AND MODULATION OF LIGHT BEAMS Filed May 22, 1941 2 Sheets-Sheet 2 Patented Mar. 28, 1944 n TRANSBIISSION AND MODULATION OF LIGHT BEAMlS Ben F. Atwood, Lakeland, Fla.

Application May 22, 1941, Serial No. 394,721

( Cl. Z50-7) 6 Claims.

My invention relates generally to signaling means, and particularly to the use of light beams as carrier media for intelligence, and the primary object of my invention is to provide simple and emcient means for the modulation of and transmission of suitable light beams.

Other important objects and advantages of my invention will be apparent` from a reading of the following description taken in connection with the appended drawings, wherein for purposes of illustration I have shown preferred embodiments of my invention.

In the drawings:

Figure 1 is a general schematic view showing the coupling of a conventional amplifier to a dynamic or magnetic reproducing unit having its voice coil or vibrating arm physically connected to a light reflecting medium, such as a diaphragm.

Figure 2 is a similar schematic view of an arrangement in accordance with the present invention involving the projection of a powerful light beam by means of a searchlight or other suitable source oi visible or invisible light rays. in a beam in which is interposed edgewise a disk connected to a vibrating arm having physical connection to a voice coil of a dynamic or magnetic output unit, and coupled to a suitable amplifying unit.

Figure 2a is a modiiication of the arrangement shown in Figure 2 of the drawings, employing a. translucent bead instead of a disk type diaphragm.

Figure 3 is a schematic illustration of a twoway light beam communication system wherein only one station is provided with a light source and energizing power supply for said light source.

Figure 4 is a schematic representation of a signal system characterized by an arrangement suitable for use with any of the foregoing embodiments of the invention, wherein the light beam is conducted and carried non-axially or bent by a rod or series of rods of light conductingmaterial.

In Vaccordance with the present invention one method of transmitting and receiving employs an amplifier for reproducing voice, music, or other trating the beams of visible or invisible light are achieved. Thus when a signal is introduced into the amplifier the reecting medium coupled to the output is caused to vibrate more vigorously and with greater strength in accordance with the input signal than would be possible with the direct methods heretofore used, wherein the feeble sound waves directly vibrate the diaphragm.

Another method contemplates the employment of a light source and means for energizing the light source, the light source being focused within a rigid redactor similar to an efficient searchlight with a concentrating lens projecting parallel or nearly parallel beams of light onto a disk, bead, or other vibrating arm insertedinthe.

path or' light beams and rigidly connected to a voice coil or other operating arm of a dynamic or magnetic output reproduction unit, the unit being in turn coupled to a vacuum tube or other amplifying unit.

A still further arrangement in accordance with the present invention provides for the transmission of means of modulated light failing within the visible or invisible spectrum and the focusing or direction of the same onto the surface of a. polished rod of suitable light carrying and transmitting material, such as that now on the market and known by the name of "Lucite" whereby the eliective light beams may be bent and distorted so as to be emitted at a point laterally and longitudinally remote from the axial center of propagation of the light rays.

The invention further contemplates any combination or cooperation of the foregoing methods, but for purposes of disclosure and illustration the arrangements shown in the drawings and described herein below are provided in order to make clear the principles of the invention for purposes of this application.

Referring in detail to the drawings, and iirst to Figure 1 thereof the numeral 5 generally designates a conventional suitable form of microphone. phonograph or electrical pick up, radio or television transmitting medium the vibrations from lwhich are amplied by the amplifier 6 whose output is connected to the magnetic or dynamic reproducing unit 1. such as a reproducing unit used for high quality radio or sound system output. The voice coil or vibrating element 8 of this unit is rigidly attached to a reiecting diaphragm 9 within any suitable housing IU.' The diaphragm 9 may be of any suitable reiiecting material and have any suitable or desirable shape in accordance with circumstances. A light source Il is mounted in the housing l0 at one side of the axis of the transmitter beam and properly adjusted to concentrate or direct the light rays I2 onto the reiiector 9 from which rays are reflected or transmitted in a parallel beam I3 through lens I0' to a remotely located photo-electric receiving and amplifying unit which is generally designated I4 and may suitably comprise a housing I5 having a concentrating lens IB in its forward wall for concentrating the light beam on the photronic element I1 within the housing which is connected to the amplifying element I8 of suitable type whose output is conventionally connected to a suitable utilization means I9. The light rays I2 falling upon the rehector 9 which is vibrated by the amplified signal coming from the pick-up will be diffused or modulated in accordance with the vibrations, so that the beam I3 will be characterized by the modulation and correspondingly affect the photronic element II, so that the amplified output thereof available at the point I8 is in a powerful and readily adaptable form.

Referring now to the arrangement of the invention shown in Figures 2 and 2a the numeral l2i] generally designates a suitable current source for a powerful light producing element IIa producing visible or invisible light within a suitable reecting and concentrating casing Illa involving the concentrating lens Illa in advance of a tubular portion 2| having the general cross section of the transmitted beam 13a. In this tubular portion 2I is supported a disk 23, placed edgewise, in the light beam I3a and having rigidly connected thereto the vibratory arm 24 which is operatively connected to the voice coil 8a of an electro-magnetic output unit 1a, the voice coil being electrically connected to the amplifying unit 25 having a plurality of input elements such as those indicated by the numerals 26, 21 and 28. 1n this arrangement the operation of the amplifier unit 25 causes the voice coil 8a to very powerfully vibrate the arm 24 and consequently the disk 23, and correspondingly greatly modulate the light beam I3a as it moves toward the receiving unit Mawhich may be similar to the photronic unit of the first described embodiment.

Referring to Figure 2a of the drawings, this is an arrangement substantially similar to that shown in Figure 2 of the drawings, but employs a glass or other translucent material bead 23 instead of the edgewise disk 23, with substantially similar operative effects, a suitable field supply 2 8 being connected in both cases to the field of the unit 1a or 'I', and a suitable source of current (not shown) being provided -for thevam plifying units 25 and 25'. y

Referring now to the embodiment of the invention shown in Figure 3 of the drawings showing a two-way light beam communication system, a single light source IIb, such as an electric arc, is provided at the home station and mounted in a suitable housing Ib, the housing being of a light concentrating and reecting type having mounted axially therein a conical vibrating refiector diaphragm 9b operatively connected to the voice coil 8b of a reproducing unit 1b, the crater of the arc being located in axially alignment with the axis of the reector 9b and a suitable source of energy 29 being provided for energizing the are.

A held supply for the unit-'Ib is designated 26h. A suitable amplifying unit Bb has its input varied by a microphone or other similar arrangement, :.s in the above described embodiments of the invention, and has its output connected to a suitable utilization means I9b. In this instance also the amplider 6b is connected to the coil 8b. The remote away station I4b is constructed similarly to the home station described.

In both stations the housings Ib and IU' have mounted thereon the sub-housings 30 and 30' containing photronic receiving element 3l in conjunction with concentrating lens 32 and 32', the same being laterally displaced with respect to the main light beam I3o. It is to be noted, however. that the remote station |40 does not have a light source IIb like the home station.

The remote station shown to the right in Figure 3 is the drawings, utilizing the beam I3b from the transmitting home station, can reflect and retransmit the beam I3b by means of the collecting and transmitting reflector 9' to the receiving section. 3U of tne original transmitting station, the remote station causing the reflector 9 to suitably modulate the reflected light beam so as to convey intelligence to the receiving section 30 and its component parts at the home station. Similarly the modulated beam from the light transmitter 9b which is modulated by the modulating unit 'ib is picked up at the remote station by the light detecting and reproducing unit 30'. The elements 30 and 30' and the photronic elements 3I and 3|', energized from the respective amplifiers 6b and 6' are so placed that the local beams from their own transmitting stationscannot be detected by them. When a signal from a suitable amplifier is caused to flow through the dynamic or magnetic reproducing unit 7b in reproducing sound or 1i `rations or other frequencies and whose voice coil or vibrating arrangement 8b, 8b has its arm securely attached to the modulating reector 9b, the energized or modulated light from the are I Ib falling upon the mirror light surface of the vibrator reflector 9b will be projected in a correspondingly modulated form to impinge on the vibratory reflector S' of the remote unit which is arranged to reflect some of the light to operate the unit 30 on the home station. It will be understood that the remotel station does not have a light source of its own, but depends for transmission to the home station upon reflecting and modulating a portion of the light beam originating at the home station, and at such times as the light beam is projected to the remote station in unmodulated condition.

Referring now to the embodiment of the invention shown in Figure 4 of the drawings, the numeral I0c generally designates a modulated light beam transmitter and the numeral 35 a rod, tube or section of Lucite or other similar light con. ducting material. When the light transmitted from the unit Ib impinges on the element 35, the opposite end of the element, wherever located with respect to the original axis of projection of the light, will emit the transmitted light so that it is capable of being detected and amplified by asuitable photronic amplifying unit which is generally designated I4. In this way the transmission of a light beam is possible without the transmitting vstation being within visual range or axial alignment, and without the use of reectors, prisms, or similar light bending devices.

Although I have shown and described herein preferred embodiments of my invention, it is to be definitely understood that I do not wish to limit the application of the invention thereto ex cept as may be required by the scope of the sub- Joined claims.

source and projecting the same to the remote station modulated by the operation ofrsaid light reflecting means, and light affected means at the remote station operated by the said light beam while unmodulated, means at the remote station for reflecting back to the home station a portion of the original light beam. means at said remote station for modulating said reflected portion of the original beam, and additional light aected means at said home station operated by the modulated reflected portion of the original light beam.

2. A transmitting and receiving system comprising a pair of transmitting and receiving stations, light beam producing means at one of the stations for projecting a light beam toward the other station. each station comprising high frequency means for modulating the light beam, amplifying means including light affected means for exposure for actuation to a modulated light beam coming from the other station, the sta-tion Without light beam producing means having light reflecting means operative to receive and reect the light beam from the other station back to the light affected means of said other station only While said light beam is unmodulated. the station devoid of light beam producing means having its high frequency modulating means arranged to modulate the beam reflected back to the other station while the modulating means of said other station is inoperative.

3. A transmitting and receiving system comprising a home station comprising light beam producing and projecting means for directing a beam of light toward the remote station, high frequency means for modulating said light beam, and light affected means including amplifying means for recording and amplifying a modulated light beam proceeding from said remote station, said remote station comprising light reecting means for refleeting the light beam back to the light affected means of the home station while the light beam is in unmcdulated condition, said remote station further comprising means for high frequency modulating the light beam reflected to the light affected means of the home station.

system as recited by claim 3 wherein said @high frequency modulating means is responsive to sound vibrations.

5. In a method of transmission utilizing axial modulation of a unidirectional light beam as the medium of transmission to a remote station and electro-mechanical means for axially modulating the light beam, the steps of imposing the normal amplitudes and frequencies of the intelligence to be transmitted directly upon a medium responsive thereto, substantially amplifying the output of suchmeclium, and operating said electro-mechanical means by means of the amplined output, the resultant modulation of the light beam merely being controllable by controlling the am pliiication of the original intelligence.

6. The method of transmitting intelligence by means of a modulated light beam directed toward a remote receiving station which consists in directly imposing the normal frequency and amplitudes of the intelligence to be transmitted upon a medium responsive thereto, amplifying the'out; put of such medium, and electro-mechanically imposing the amplified resultant upon the light beam in a manner to modulate the main portion of the light beam principally axially.

BEN F. ATWOOD. 

